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. 2021 Jul 9:12:702839.
doi: 10.3389/fmicb.2021.702839. eCollection 2021.

Continual Decline in Azole Susceptibility Rates in Candida tropicalis Over a 9-Year Period in China

Yao Wang  1   2   3 , Xin Fan  4 , He Wang  3 , Timothy Kudinha  5   6 , Ya-Ning Mei  7 , Fang Ni  7 , Yu-Hong Pan  8 , Lan-Mei Gao  8 , Hui Xu  9 , Hai-Shen Kong  10 , Qing Yang  10 , Wei-Ping Wang  11 , Hai-Yan Xi  11 , Yan-Ping Luo  12 , Li-Yan Ye  12 , Meng Xiao  1   2   3 ; China Hospital Invasive Fungal Surveillance Net (CHIF-NET) Study Group
Collaborators, Affiliations

Continual Decline in Azole Susceptibility Rates in Candida tropicalis Over a 9-Year Period in China

Yao Wang et al. Front Microbiol. .

Abstract

Background: There have been reports of increasing azole resistance in Candida tropicalis, especially in the Asia-Pacific region. Here we report on the epidemiology and antifungal susceptibility of C. tropicalis causing invasive candidiasis in China, from a 9-year surveillance study.

Methods: From August 2009 to July 2018, C. tropicalis isolates (n = 3702) were collected from 87 hospitals across China. Species identification was carried out by mass spectrometry or rDNA sequencing. Antifungal susceptibility was determined by Clinical and Laboratory Standards Institute disk diffusion (CHIF-NET10-14, n = 1510) or Sensititre YeastOne (CHIF-NET15-18, n = 2192) methods.

Results: Overall, 22.2% (823/3702) of the isolates were resistant to fluconazole, with 90.4% (744/823) being cross-resistant to voriconazole. In addition, 16.9 (370/2192) and 71.7% (1572/2192) of the isolates were of non-wild-type phenotype to itraconazole and posaconazole, respectively. Over the 9 years of surveillance, the fluconazole resistance rate continued to increase, rising from 5.7 (7/122) to 31.8% (236/741), while that for voriconazole was almost the same, rising from 5.7 (7/122) to 29.1% (216/741), with no significant statistical differences across the geographic regions. However, significant difference in fluconazole resistance rate was noted between isolates cultured from blood (27.2%, 489/1799) and those from non-blood (17.6%, 334/1903) specimens (P-value < 0.05), and amongst isolates collected from medical wards (28.1%, 312/1110) versus intensive care units (19.6%, 214/1092) and surgical wards (17.9%, 194/1086) (Bonferroni adjusted P-value < 0.05). Although echinocandin resistance remained low (0.8%, 18/2192) during the surveillance period, it was observed in most administrative regions, and one-third (6/18) of these isolates were simultaneously resistant to fluconazole.

Conclusion: The continual decrease in the rate of azole susceptibility among C. tropicalis strains has become a nationwide challenge in China, and the emergence of multi-drug resistance could pose further threats. These phenomena call for effective efforts in future interventions.

Keywords: Candida tropicalis; antifungal resistance; antifungal susceptibility; azole; echinocandin.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Trends of azole susceptibility in C. tropicalis over a 9-year surveillance. S, susceptible; R, resistant; WT, wild-type; NWT, non-wild-type.
FIGURE 2
FIGURE 2
Number of isolates collected in seven administrative regions of China (labeled by different colors), and proportion of fluconazole susceptible (S), susceptible dose-dependent (SDD), and resistant (R) isolates in each region.
See this image and copyright information in PMC

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